1. Field of the Invention
The present invention relates to an impact-absorbing pressure-sensitive adhesive sheet and to a method of producing the same. More specifically, the present invention relates to an impact-absorbing pressure-sensitive adhesive sheet to be used for an image display apparatus such as a liquid crystal display apparatus and to a method of producing the same.
2. Description of the Related Art
A liquid crystal display apparatus must have polarizing plates arranged on both sides of a liquid crystal panel based on its image forming system. The polarizing plates to be used are each generally prepared by attaching a protective film on both surfaces of a polarizer. Further, for optical compensation of a liquid crystal panel, an optical compensation film such as a retardation film may be arranged between the polarizing plate and a glass substrate of the liquid crystal panel.
For preventing the glass substrate from being broken by external impact, there is disclosed arrangement of an impact-absorbing pressure-sensitive adhesive layer on a viewer side of a glass substrate (see JP 2005-173462 A). It is proposed that the impact-absorbing pressure-sensitive adhesive layer is arranged on a viewer side of a polarizing plate or between the polarizing plate and the glass substrate.
In a mobile device such as a cell phone, a protective layer formed of a plastic sheet or the like is generally provided on a viewer side of a liquid crystal display. Further, for preventing the liquid crystal display from being broken by external impact, a space (air layer) is provided between the liquid crystal display and the protective layer. However, there is a problem in that reflection occurs at an interface between the protective layer and the air layer and an interface between the air layer and the liquid crystal display to cause degradation in viewing properties. Thus, for assuring impact resistance, improving the viewing properties, and reducing a thickness of the plastic sheet (ultimately, mobile device), the impact-absorbing pressure-sensitive adhesive layer described above is used instead of the air layer.
Meanwhile, the impact-absorbing pressure-sensitive adhesive layer is generally cut to match a size of an optical device to be applied to. However, the impact-absorbing pressure-sensitive adhesive layer typically has a thickness of several hundreds microns for obtaining sufficient impact resistance for practical use. Thus, there is a problem in that a cut surface may deform during cutting to cause adverse effects on display properties of an image display apparatus. Meanwhile, cutting in high yield is desired.